Harmonic Load Issues, Impact, and Mitigation

DSTAR Project 12-6 was initiated to investigate the changing nature of loads on electric distribution systems. The project confirmed that the utility load is becoming more active and non-linear, and as a result the loading due to harmonics created by these loads is increasing and changing. With more phase-to-neutral connected electronic loads, distribution utilities are finding that in many cases the dominant harmonic is the 3rd, which causes high neutral currents and neutral-to-ground voltages in addition to substantial increase in voltage distortion. This project will study and report on 3rd harmonic producing loads, (as well as other harmonics) and

Analyze their impact on distribution systems, with regard to thermal loading, distortion and neutral voltage elevation

Identify what mitigating measures are currently available or in development, including system design, equipment application, filters, etc.